Semiconductor devices are used in a variety of electronic applications, such as computers, cellular phones, personal computing devices, and many other applications. Home, industrial, and automotive devices that in the past comprised only mechanical components now have electronic parts that require semiconductor devices, for example.
Semiconductor devices are manufactured by depositing many different types of material layers over a semiconductor substrate or wafer, and patterning the various material layers using lithography. The material layers typically comprise thin films of conductive, semiconductive, and insulating materials that are patterned and etched to form integrated circuits (IC's). There may be a plurality of transistors, memory devices, switches, conductive lines, diodes, capacitors, logic circuits, and other electronic components formed on a single die or chip.
Isolation regions are used to provide electrical isolation between active areas or electronic components formed on an integrated circuit. Shallow trench isolation (STI) and deep trench (DT) isolation are examples of some types of isolation regions that are widely used in semiconductor devices, although there are other types of isolation regions that may be formed.
STI regions are often used in complementary metal oxide semiconductor (CMOS) devices, which use both positive and negative channel devices in complementary configurations. The positive and negative channel devices of CMOS devices are typically referred to as p channel metal oxide semiconductor (PMOS) and n channel metal oxide semiconductor (NMOS) transistors. The PMOS transistor is formed in an n well (e.g., a well implanted with n type dopants) and the NMOS transistor is formed in a p well. An STI region is formed between the n well and p well of the PMOS transistor and the NMOS transistor, respectively. The STI region usually extends within a semiconductor substrate by about the depth of the maximum n well and p well doping concentration, e.g., by about 0.2 to 1.0 μm, for example.
To form isolation regions, trenches are usually formed in a substrate, and the trenches are filled with insulating materials. Etch processes and chemical mechanical polishing (CMP) processes are used to remove excess insulating material from the top surface of the substrate.
One problem that often occurs in the formation of isolation regions is the formation of recesses or divots in the insulating material used to fill the trenches. The lack of insulating material in the recessed or divoted areas can result in inadequate electrical isolation between active areas and undesired topography being formed on the top surface of the substrate.
Another problem that can occur is difficulty in filling trenches having a high aspect ratio, wherein the depth is greater than the width.
Thus, what are needed in the art are improved methods of forming isolation regions and structures thereof.